fix bug with response body, add test for download hash

client/tests/scripts/test_download_hash.js

@@ -0,0 +1,20 @@
+//https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/digest#examples
+async function digestMessage(msgUint8) {
+  const hashBuffer = await window.crypto.subtle.digest("SHA-256", msgUint8); // hash the message
+  const hashArray = Array.from(new Uint8Array(hashBuffer)); // convert buffer to byte array
+  const hashHex = hashArray
+    .map((b) => b.toString(16).padStart(2, "0"))
+    .join(""); // convert bytes to hex string
+  return hashHex;
+}
+
+async function test() {
+  let url = "https://curl.se/download/curl-8.11.0.tar.gz";
+  let expected_hash = "264537d90e58d2b09dddc50944baf3c38e7089151c8986715e2aaeaaf2b8118f";
+
+  let r = await libcurl.fetch(url);
+  let msg = new Uint8Array(await r.arrayBuffer());
+  let hash = await digestMessage(msg);
+
+  assert(hash === expected_hash, "unexpected hash of downloaded data");  
+}